1. Field of the Invention
The present invention relates to a vapor-compression-type refrigerating machine for moving heat from a portion on the low temperature side to a portion on the high temperature side. The vapor-compression-type refrigerating machine of the present invention is effectively applied to an air conditioner for vehicle use.
2. Description of the Related Art
As well known, the vapor-compression-type refrigerating machine operates as follows. A liquid phase refrigerant is decompressed by an expansion valve, and the refrigerant, the pressure of which has been reduced, is evaporated so as to absorb heat, and the thus evaporated refrigerant, the phase of which has become a gas phase, is adiabatically compressed by a compressor so that the temperature can be raised and the heat absorbed in the process of evaporation can be radiated.
It is conventional that the expansion valve is provided with a spring for giving a pre-load (initial load) to the valve body which adjusts the degree of throttle opening so that the degree of superheat of the refrigerant sucked into the compressor can be in a predetermined range. Concerning this technique, for example, refer to the official gazette of Japanese Unexamined Patent Publication No. 2002-213842.
In this connection, the expansion valve is composed of a plurality of parts such as a diaphragm, valve body and so forth. Usually, the maximum displacement of the valve body is not more than 1 mm, that is, the maximum displacement of the valve body is very small. Accordingly, even if the dimensional fluctuation of parts composing the expansion valve is small, operation of the valve body can be greatly affected.
Therefore, it is conventional to provide a pre-load adjusting mechanism for adjusting a pre-load (initial load) given to the valve body or diaphragm by a spring. When the pre-load adjusting mechanism is adjusted after all parts have been assembled, the pre-load is adjusted so that the valve body can be appropriately operated.
According to the expansion valve described in the official gazette of Japanese Unexamined Patent Publication No. 2002-213842, the pre-load adjusting mechanism is provided. It is necessary to adjust the pre-load adjusting mechanism after all parts have been assembled. Therefore, it is difficult to decrease the number of parts of the expansion valve. Further, it is difficult to reduce the number of processes in the manufacturing process.